The invention relates to an image detector having                a sensor matrix which includes        plurality of sensor elements for converting radiation into electrical charges,        several line conductors,        separate sensor elements being coupled to at least one of the line conductors, and        the sensor elements being arranged in columns and rows.        
The invention also relates to an X-ray examination apparatus including                an X-ray source for emitting an X-ray beam and        an X-ray detector for receiving an X-ray image and deriving an image signal from the X-ray image.        
The image detector derives an image signal from an image, the signal levels of the image signal representing brightness values of the image. When radiation, such as light or X-rays, is incident on the sensor elements, electrical charges are generated in the sensor elements. The quantity of the electrical charge in individual sensor elements corresponds to the intensity of the radiation that is incident on the relevant sensor element. The electrical charges in the sensor elements are detected, i.e. read-out, along the read-lines and the image signal is formed from the read-out electrical charges. The signal levels of the image signal correspond to the electrical charges and hence to the radiation intensities received at the respective sensor elements. The signal levels of the image signal thus correspond to the brightness values of the image such as a visible image or an X-ray image.
Such an X-ray examination apparatus and such an image detector are known from the patent U.S. Pat. No. 5,184,018.
In the known image detector all sensor elements in individual columns are coupled to a single read-line and all sensor elements in individual rows are coupled to a single addressing line. Should one of the read-lines and/or one of the addressing lines in the known image detector become defective, a serious error would occur in the image signal. More specifically a defect in a read-line or in an addressing-line, causes the exclusion of the brightness values of an entire vertical or horizontal line in the image from the image signal. It has been found that it is very difficult to correct this error in the image signal and that, after an attempt to correct the image signal, a substantial residual error remains. As an alternative for the known image image sensor there are provided two read-lines per column, the different read-lines carrying the collected charges to opposite sides of the substrate of the image sensor.